The Bastokan guards (I.M - Iron Muskateer) who cast signet on Bastokan's and any allies (not that that happens very often) are the people who sell these mittens for Conquest points...
Remember this - (because it seems not many people even KNOW this)
Conquest items can only be bought from another nations guards IF your nation has a higher CONQUEST ranking than the nation you are attempting to buy them from.
Bare in mind, for a Bastokan they will cost 1000 conquest points however, for any other nation they will cost 2000.
They are also sold on AH... personally, i got mine and kept them for a long time since i'm not sure when i'll be done with them.
Hope i helped a bit...
Karixi